1. Field of the Invention
This invention relates to arrangements for providing capacitive crosstalk compensation coupling among signal paths in high frequency communication connectors.
2. Discussion of the Known Art
There is a need for a durable, high frequency communication connector that compensates for (i.e., cancels or reduces) crosstalk among and between different signal paths through the connector. As broadly defined herein, crosstalk occurs when signals conducted over a first signal path, e.g., a pair of terminal contact wires associated with a communication connector, are partly transferred by inductive and/or capacitive coupling into a second signal path, e.g., another pair of terminal contact wires in the same connector. The transferred signals define "crosstalk" in the second signal path, and such crosstalk degrades any signals that are being routed through the second path.
For example, an industry type RJ-45 communication connector has four pairs of terminal wires defining four different signal paths within the connector. In typical RJ-45 plug and jack connectors, all four pairs of terminal wires extend closely parallel to one another over the lengths of the associated connector bodies. Thus, signal crosstalk may be induced between and among different pairs of terminal wires within the typical RJ-45 plug and jack connectors, particularly when the connectors are mated to one another. The amplitude of the crosstalk becomes stronger as the coupled signal frequencies or data rates increase.
Applicable industry standards for rating the degree to which communication connectors exhibit crosstalk, do so in terms of so-called near end crosstalk or "NEXT". Moreover, NEXT ratings are typically specified for mated connector configurations, for example, a type RJ-45 plug and jack combination, wherein input terminals of the plug connector are used as a reference plane.
Communication links using unshielded twisted pairs (UTP) of copper wire are now expected to support data rates up to not only 100 MHz, or industry standard "Category 5" performance; but to meet "Category 6" performance levels which call for at least 46 dB near end crosstalk loss at 250 MHz.
Crosstalk compensating circuitry may also be provided on or within layers of a printed wire board, to which spring terminal contact wires of a communication jack are connected within the jack, housing. See U.S. patent application Ser. No. 08/923,741 filed Sep. 29, 1997, and assigned to the assignee of the present application and invention. All relative portions of the '741 application are incorporated by reference herein. See also U.S. Pat. No. 5,299,956 (Apr. 5, 1994).
U.S. Pat. No. 5,547,405 (Aug. 20, 1996) discloses an electrical connector having signal carrying contacts that are formed on different lead frames. Contacts from one lead frame have integral lateral extensions that overlie enlarged adjacent portions of contacts from another lead frame, to provide capacitive coupling. A dielectric spacer is assembled between an extension of one contact, and an enlarged adjacent portion of another contact. Thus, the signal carrying contacts in the connector of the '405 patent require tooling for two different lead frames, and the contacts must be properly aligned with the dielectric spacer between them during assembly of the connector.
There remains a need for a communications jack connector which, when mated with a typical RJ-45 plug connector, provides such crosstalk compensation that the mated connectors meet or surpass Category 6 performance. It would be especially desirable if such a connector could be manufactured using existing components as much as possible, and without expensive tooling or assembly requirements.